1. Field of the Invention
The present invention relates to surgical devices and methods for repairing tissue tears and, more particularly, to a device and method for repairing a meniscal tear in a knee.
2. Description of Related Art.
The menisci of the knee are C-shaped disks of cartilaginous tissue interposed between the condyles of the tibia and the femur. They are actually extensions of the tibia that serve to deepen the articular surfaces of the tibial plateau to accommodate better the condyles of the femur (see FIG. 1). The material of the menisci is collagenous, and the fibers are oriented generally circumferentially.
As the menisci were long considered functionless remains of leg muscle, injury to this tissue had been treated by their total removal, called meniscectomy. A better understanding of these structures, combined with improvements in arthroscopic surgical techniques, has led to the development of meniscal repair techniques.
Posterior peripheral tears of the menisci may be treated by an open technique, wherein sutures are placed along the tear. An arthroscopic technique may also comprise placing sutures along the tear, but in this method through a cannula.
There are a number of fastener-type devices that are known in the art. A surgical fastener is disclosed by Screiber (U.S. Pat. No. 4,873,976) that comprises a shaft having at least one barb for locking the shaft in place when inserted into soft tissue. Also described is an applicator consisting of a cylinder into which the fastener is placed and out of which the fastener is pushed when positioned at the tear site.
Bays et al. (U.S. Pat. Nos. 4,884,572 and 4,895,148) describe a surgical-repair tack and applicator and method of using them.. The tack has a barb member and is made of biodegradable material having a degradation time,selected to coincide with the healing time of the tissue. In an alternate embodiment, the tack's barb comprises a continuous helical barb.
The method and apparatus for repairing a meniscal tear disclosed by Winters (U.S. Pat. No. 5,059,206) comprises a fastener having protrusions or barbs that is applied to a meniscal tear with a delivery device. The delivery device has a flexible tip that is manipulable through a curved radius to enable the surgeon to insert the device into the central part of the knee and then extend the fastener radially outward into and across a meniscal tear.